Fuel and air mixing device



Jan, 17, 1939. G. wf Pom-lus, JR 2,143,958

FUEL AND AIR MIXING DEVICE l Filed Jan. 2, 1956 Patented Jan. 17, 1939UNITED sTATEs v,2,143,958 FUEL ANDEAm MIXING DEvxcE George W. Pontius,Jr., South Bend, Ind., assignor to International EngineeringCorporation, Chicago, Ill., a corporation of Illinois ApplicationJanuary 2, 1936, Serial No. 57,115=

2 Claims.

This invention relates to the mixing of air and fuel, for liquid-fuelburners' and the like, and is illustrated as embodied in burner nozzlesfor domestic or industrial oil burners. An object of the invention is toprovide simple and effective means for atomizing a liquid fuel by aprimary air stream under pressure, and then mixing an adequate supply ofsecondary air with the stream of mixed fuel andprimary air, resultl0 ingin a combustible mixture.

In one desirable arrangement, the air is fed under pressure into an airbox mounted on the end of the fuel conduit, the fuel and primary airbeing mixed at the end of the air box opposite that ,mounted on theconduit and being projected axially outward, while the secondary air isled from the air `box and directed into the axiallyprojected stream ofmixed fuel and primary air. The secondary air may, if desired, beprojected with a whirling motion through a series of jets.

In several. effective and simple embodiments, the fuel is fed, in a thinfilm crosswise'of a stream of primary air projected outwardly throughthe l central portion of the fuel illm, thus giving very effectiveatomization of the fuel.- Advantage may be taken of this arrangementtoutilize the ilimforming means to cooperate with the side wall of the airbox to dene an annular discharge passage for the secondary air.

The above'and other objectsandv features of the invention, includingvarious novel combinations of parts and desirable particularconstructions, will be apparent from the following description of theillustrative embodiments shown in the accompanying drawing, in which:

Figure 1 is a longitudinal section through one.

embodiment;

Figure 2 is a similar section, on a larger scale, of the means fordirecting the blast of primary air through the film of fuel; and

Figures 3 and 4 are sections corresponding to Figure 1, but showingmodifications.

The device shownin Figures l and 2 comprises a fuel conduit Ill, closedby a suitable plug or integral web l2 some distance from its end. Onthis conduit is threaded, or otherwise mounted, va sleeve I4 formedaxially of the bottom of a cup-shaped air box i6. Air under pressure isfed into the box I6 through a suitable connection I8. The box I6 and theconduit l0 define between them an annular reservoir space for the air.

Beyond the web I2, the conduit l0 is formed with an opening 20 on itsside, through which the air enters from the box I6, to pass in a primaryair stream out through the end of the conduit,

through a central' conical opening 22 in a fuel `distributor 24threadedly mounted on the end of the conduit IU. This distributor isformed with an annular groove 26 communicating by means such as a smallconduit 28 with the fuel supply in the conduit I0 at the right of theplug I2.

,The distributor 24 has mounted over and spaced slightly from its face aplate 30, formed with a. central opening alined with the opening 22.This defines a narrow space through which the fuel flows in a thin lmcrosswise of the primary air stream, which is thus projected through thecentral portion of the fuel film axially outward and to the left inFigures 1 and 2.

The stream of mixed fuel and primary air passes out through the flaringcentral opening of an annular cap 32 which is threaded onto theperiphery of the distributor 24, and which also serves to clamp theplate 30 in place over the face of the distributor. i

It will'be noted that in\this embodiment, as well as in thosehereinafter described, the film of fuel extends transversely across whatis in effect the neck of a venturi through which the air is flowing.This produces a suction on the fuel line which aids in feeding the fueland which, if the lift is not great, can even in some cases be used asthe sole agency for feeding the fuel.

The periphery of the cap 32, and a slightly conicallyconverging cap 34threaded onto and in effect forming a continuation or part of thecylindrical side wall of the air box I6, together define an annularpassage directing outwardly a stream of secondary air which envelopesand surrounds and quickly mixes with thecentral stream of mixed fuel andprimary air.

The parts of the embodiment of Figure 3 which correspond to those ofFigure 1 are designated by the same reference characters increased by100. This embodiment has its distributor |24 arranged at the end of theassembly, and carried by an annulus |32 having a flared central pri-'mary air passage. The annulus |32 has secured thereto a cupshapedstamping ||2 formed with an air opening |20, and having welded to itsbase a nut |36 threaded on the end of the conduit IIB.` The airbox inthis case has the converging conical portion |34 integral with its sidewall, and has a detachable base |38.

'I'he modification of Figurel 4 has the parts corresponding to those inFigure .ldesignated by the same' reference characters increased by 200.In this embodiment the wall 234 which directs the'secondary air flaresslightly, instead of converging, so that the mixture is formed moreslowly. I'his is suitable for use in a larger fire box.

While several illustrative embodiments have been described in detail, itis not my intention to limit my invention to those particularembodiments, or otherwise than by the terms of the appended claims.

I claim:

1. An air and fuel mixing device comprising an air box having an openendand provided with an inlet for air under pressure, a conduit forliquid fuel under pressure extending through the closed end of the boxand the end of which is closed, a pair of generally disk-shaped partswhich are secured together and mounted on the end of the fuel conduitinside said box adjacent its open end and the periphery of one of whichparts is spaced a short distance from the interior of the boxto providean annular passage for secondary air, said 'parts being in sealingcontact with each other in an annular zone just inside said annularpassage and being formed just inside said zone with an annular grooveand being spaced apart a short distance within said groove so that fuelowing from said groove will form a film crosswise of the air box, saidparts having registering central openings communieating with. theinterior of the air box to form a passage for primary air whereby suchprimary air may pass through said lm, and means conx necting saidannular groove to the interior of the fuel conduit to receive fueltherefrom.

2. An air and fuel mixing device comprising an air box provided with aninlet for air under pressure, a conduit for liquid fuel under pressureextending through one end of the box and the end of which is closed, adevice mounted on the end of the fuel conduit inside said box adjacentits other end and which is smaller than said air box to afford passagefor secondary air, said device being formed just inside its peripherywith an annular groove and with a space within said groove such that'fuel flowing from said groove will form a film crosswise of the air box,said device having a central opening communicating with the interior ofthe air box to form a passage for primary air whereby such primary airmay pass-through said film, and means connecting said annular groove tothe interior of the fuel conduit to receive fuel therefrom.

GEORGE W. PONTIUS, JR.

